There are five bones in the human skeleton called vertebral bodies that comprise the structure of the lumbar spine. These bones are normally in a structure which allows them to be stacked on top of one another much like building blocks. In this relationship, and through their interlocking structure, the spine can bend forward, called flexion, or bend backwards, called extension. It can bend to either side, called lateral bending, and it can also twist or rotate. These ranges of motion are facilitated by muscles which attach to the lumbar vertebrae and these motions are stabilized not only by the bones themselves but by ligaments and discs which attach to these vertebrae.
In the course of human development, human deterioration and various disease processes and trauma, the alignment of the spine can be altered in such a way that one or more bones might become loose on one another causing an instability problem. The medical term for this problem is spondylolisthesis. The vertebral bodies also might develop a curvature problem called scoliosis. The development of arthritic spurs may also distort spinal configuration. Fractures, tumors, infections, and extensive surgical procedures can also distort spinal anatomy and spinal integrity resulting in the development of deformities of the lumbar spine.
In the last 30 years, a great deal of work has been done in orthopaedics on the development of procedures to stabilize deformity in the lumbar spine, and more recently to correct that deformity. The reason to correct the deformity is that the lumbar spine serves in many ways as a foundation on which the remaining structure of the thoracic and cervical spine exists. Having the lumbar spine in a more appropriate position allows for more normal functioning of the spinal structure above it.
Surgery is sometimes required to realign the spine. Generally, the surgeon will cut into the back of the patient to access the spine. He will use a retractor to hold skin and muscle away from the spine to improve his access to the spine. To align a lumbar vertebra, a screw called a pedicle screw will be inserted into the pedicle portion of a lumbar vertebra. Then the surgeon will pull on the pedicle screw to move the lumbar vertebra into appropriate alignment. Usually, internal hardware will then be attached to the spine to maintain proper alignment. To avoid trauma to the muscles, ligaments and nerves attached to the spinal cord, it is very important that the vertebra not be yanked into alignment. However, accomplishing this objective is easier said than done. Occasionally, with the pressure that is required to "pull" the vertebra into alignment, when the resistance to realignment is overcome, the surgeon cannot react quickly enough to prevent the vertebra from being yanked. In fact, gradual, even pressure on the vertebra is difficult to accomplish, thus making the surgery one of greater risk to complication than is desirable.
What is needed is a device to allow the surgeon access the pedicle screw from various angles and a platform and device which will enable the surgeon to apply even pressure on the vertebra as it is pulled into alignment without "yanking" the vertebra into place.
The device should be one which can be manipulated through multiple degrees of freedom to align with the pedicle screw is needed.
The device must enable the surgeon to apply a steady, gently, increasing tension to the pedicle screw during the alignment process.
The device should allow the surgeon to concentrate on the delicacies of the procedure, rather than muscling a vertebra into position.
The device should allow the surgeon to make minute adjustments to vertebra during spinal surgery to reduce the risk of back surgery to a patient.
Such a device would preferably maintain spinal alignment while the surgeon attaches in-dwelling hardware.
A device satisfying these needs is believed to be lacking in the prior art.